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Box-shape cervical expansive laminoplasty is a procedure that utilizes a Miniplate® or Maxpacer® to achieve maximal canal expansion. This method is expected to show much larger canal expansion and good clinical outcome. So we investigated the clinical and radiological outcome of Box-shape cervical expansive laminoplasty.
Between June 2008 and July 2013, we performed cervical expansive laminoplasty in 87 and 48 patients using the Box-shape cervical expansive laminoplasty, respectively. We analyzed the clinical results of these operations using the Japanese Orthopedic Association (JOA) scoring system and by assessing the position of intralaminar screws with postoperative computed tomography (CT) at POD-6 months.
A total of 48 patients with ossification of the posterior longitudinal ligament (OPLL) (36 pts), cervical spondylotic myelopathy (CSM) (12 pts) were enrolled. Overall JOA scores improved from 11.49 to 14.22 at POD-6 months (OPLL: 11.32 -->14.3; CSM: 12-->14). Postoperative CT scans were performed in 39 patients at 177 levels for a total of 354 screws. The malpositioning rate of intralaminar screws was 3.4% and hardware-related neurologic complications did not occur.
Box-shape cervical expansive laminoplasty creates maximal spinal canal expansion and leads to improved cervical myelopathy. The use of intralaminar screws to fix the remodeled lamina-facet does not represent a significant difficulty.
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The aim of this study was to compare geometrically cross-sectional areas of two different laminoplasty techniques in same opening size.
Some investigators have studied the expanded areas of the two different techniques using imaging study. Although it is unclear that postoperative spinal canal is correlated with the surgical outcome we just focused on mathematical and geometrical correlation of the expandable area with surgical opening size in different laminoplasty techniques.
To predict the expandable area by a midline splitting technique and a unilateral open door technique, we placed an imaginary isosceles triangle in the spinal canal and drew graphs for the equation of the expandable areas in same opening size using the Pythagorean theorem and mathematical program. To substitute the constant figures of mathematical formula we estimated the normal cervical spine CT scans of 50 Korean adults.
We subtracted the imaginary triangle from the spinal canal and were left with the remaining area of the spinal canal that was not changed before and after surgery. In same opening size the expandable area by the midline splitting technique was same but slightly wider than the unilateral open door technique, irrespective of the triangular shape. For a normal isosceles triangle the results were the same.
Using mathematical proof, the expandable area after the midline splitting technique was same but slightly larger than that after the unilateral open door technique, irrespective of the size of the lamina opening.
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The aim of this study is to introduce the surgical method with miniplate and compared the expansion rate of the spinal canal area with other kinds of lamina spacers.
Between June. 2008 and May 2011, we performed expansive cervical laminoplasty on 61 patients. We analyzed the results of these operations, examining type of lamina spacer used, spinal canal areas between pre- and postoperative CT scans, and operative methods.
39 patients were analyzed retrospectively. Miniplates were used in 21 patients with 103 levels. Hydroxyapatite (HA) was used in 6 patients with 29 levels, and Centerpiece® was used in 12 patients with 54 levels. The expansion area was calculated using Photoshop CS3®. The expansion rate of the miniplates was 76.5%, that of HA was 49.8%, and that obtained with Centerpiece was 50.6%. The excellent 90° box-shaped widening of the laminae achieved through the surgery can be checked easily by AP X-ray. All miniplates are positioned horizontally and parallel, and the lamina is seen as a pedicle of thoracic or lumbar spine due to its 90° erect position. Neurologic improvement and clinical outcomes will be discussed. No complications were reported with miniplates.
Box-shaped laminoplasty with miniplates is the widest spinal canal expansion method among the three types of implants examined.
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To establish normative data for spinal canal AP diameter from cervical vertebra to sacrum in the Korean young and to assess the exposed spinal canal after laminectomy which was related with restenosis by post-laminectomy membrane formation.
From PET/CT, axial bone-window CT of 83 young adults (20-29 years) were obtained, and we measured AP diameters of C3, C5, C7, T1, T4, T8, T12, L1, L3, L5 and S1. We also measured exposed AP diameter of C3, C5, C7, T1 and T2 above imaginary line for laminectomy.
The shortest mean AP diameter was at C5 (14.5±1.5 mm), and the longest was at S1 (17.4±2.3 mm). AP diameter increased from C3 (14.6±1.1 mm) to T1 (16.1±1.2 mm) at cervical spine. In the thoracic spine, the diameter gradually decreased from T1 (16.1±1.2 mm) to T8 (14.6±1.3 mm) and increased to T12 (16.7±1.2 mm). The diameter decreased from L1 (16.7±1.3 mm) to L3 (15.7±1.9 mm), and it increased to S1 (17.4±2.3 mm) at lumbar spine. Exposed AP diameter above imaginary line for laminectomy was the longest at C3 (4.8±1.2 mm) and gradually decreased to T1 (3.3±0.9 mm) and T2 (0 mm).
Spinal AP diameter was the shortest in the mid-cervical area (C5) and increased to the upper thoracic area. From the upper thoracic vertebra, the diameter gradually decreased to the mid-thoracic vertebra (T8) and then increased to the lower thoracic vertebra. Lumbar vertebra also was similar with thoracic vertebra. Below T2, there was no exposed dural sac after laminectomy. This means that restenosis by post-laminectomy membrane formation can occur above T1.
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